Apparatus and method for pressurizing materials

ABSTRACT

A method of treating materials, and apparatus for use in the method, wherein a high-pressure torsion press in the form of a heavy wall tube having a coaxial throughbore is loaded with a charge of raw material and then the charge is confined by seal plugs secured at the ends of the bore. High pressures are exerted on the material by applying oppositely directed torsional couples to the opposite ends of the tube. This counterrotational torsional stress tends to twist the tube which in turn tends to axially shorten and radially contract the charge cavity so that the walls of the cavity apply omnidirectional compression forces on the charge of a very high magnitude. The charge is preferably also heated for a suitable time period while being pressurized to convert the charge to crystalline form, e.g., graphite to diamonds, or to otherwise modify its properties.

I United States Patent 13,630,727

[72] Inventor Peter F. Rossmann FOREIGN PATENTS 3 wg f mg Wm 207,955 5/1955 Australia arms, 211 Appl. NO. 666,674 T REFERENCES [22] Filed Sept 11, 1967 Bridgman, ScIentIfic American" l93, Nov. 1955, pp. 42- 451 Patented Dec. 28, 1971 46 Primary Examiner-Carl D. Quarforth Assistant ExaminerBrooks l-l. Hunt [54] AND METHOD FOR PRESSURIZING Attorney-Barnes, Kisselle, Raisch & Choate 8 Claims, 14 Drawing Figs.

[52 us. Cl 75/214, ABSTRAC A mum! eating materials and apparatus 264/1 1 7 5 /226 for use in the method, wherein a high-pressure torsion press in 511 1111. Cl nz'zrs/oz having a axial hmuflhbm is B22- 3/16 loaded with a charge of raw material and then the charge is 501 Field of Search 264/56 by 109, In 125 18/1, 5 16 34 pressures are exerted on the material by applying oppositely oo 5 3 2 1 29 9. 23 209 75 2 4 22 directed IOI'SlOlIBl COUPICB i0 "'16 opposite ends of the (UM. 72/299 This counterrotational torsional stress tends to twist the tube which in turn tends to axially shorten and radially Contract the [56] Relerences Cited charge cavity so that the walls of the cavity apply om- UNITED STATES PATENTS nidirectional compression forces on the charge of a very high 2 793 126 5/1957 t 1 99/172 magnitude. The charge is preferably also heated for a suitable 1'958982 5/1934 fi e a 72/299 time period while being pressurized to convert the charge to l'826077 10 1931 J ercomm 72 299 crystalline form, e.g., graphite to diamonds, or to otherwise o nson modifv its Brownies.

PATENTEU UEC28I97I $630,727

SHEET 2 [IF 2 FIG. I3 /04 FIG. IA-

A T TORNE VS APPARATUS AND METHOD FOR PRESSURIZING MATERIALS An object of the present invention is to provide an improved method for modifying the properties of solid materials by application of high pressure thereto with or without concurrent heating of the material.

Another object of the present invention is to provide an improved apparatus for use in a method of the above character which is: readily constructed of high-strength refractory metals, compact, sufficiently inexpensive to be stressed to destruction each cycle and efficiently contoured for use with electromagnetic, electrical resistance or induction heating equipment.

Other objects as well as features and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings wherein:

FIG. 1 is a semischematic perspective view of one embodiment of a high-pressure torsion press constructed in accordance with my invention.

FIG. 2 is a fragmentary vertical center section taken on line 2-2 of FIG. 1 illustrating the apparatus of FIG. 1 prior to application of torsional stresses thereto.

FIG. 3 is a vertical sectional view also taken on line 2-2 of FIG. I illustrating the stress twisted condition of the press of FIG. 1.

FIG. 4 is a perspective view of a second embodiment of the torsion press of the present invention before the twisting couples are applied.

FIGS. 5 and 6 are fragmentary vertical center sections on line 5-5 of FIG. 4 respectively illustrating the press before and after deformation by application of twisting couples.

FIGS. 7 and 8 are fragmentary vertical center sectional views of a third embodiment of an end plug respectively illustrating the unstressed and stressed conditions thereof, and FIGS. 9 and 10, FIGS. 11 and 12 and FIGS. 13 and 14 are similar paired illustrations of fourth, fifth and sixth end plug embodiments.

To better facilitate understanding, the method of my invention will in part be described in conjunction with the description of the structure and operation of the torsion press of my invention. Referring in more detail to FIGS. 1, 2 and 3, a first embodiment of a torsion press of my invention is shown in semischematic form, FIGS. 1 and 2 illustrating its unstressed condition whereas FIG. 3 illustrates the press after it has been fully stress deformed to thereby pressurize a charge of material contained therein. The principal element of press 20 is a tubular member in the form of a heavy wall hollow cylindrical shaft having a cylindrical exterior surface 22 and a coaxial throughbore 24 which form a cavity for receiving a charge of a raw material 26 to be treated in the press in accordance with the method of my invention as described in more detail hereinafter. Bore 24 preferably but not necessarily, opens at each of the opposite end faces 28 and 30 of tube 20 to facilitate loading of change 26 therein.

In most instances the charge constitutes a solid material in pellet, powder, granular or pulverant form which may be poured into bore 24 or propelled and precompacted therein by the use of suitable loading rams axially slidable into the opposite ends of bore 24. This initial compaction of charge 26 is usually sufficient to densify it to the point where it will remain temporarily in place as a compacted mass in the bore. Suitable axial spacing is provided between the opposite end faces 32 and 34 of the precompacted charge 26 and the respectively adjacent end faces 28 and 30 of tube 20.

The charge is then confined in tube 20 by sealing the ends of bore 24. Preferably this is accomplished by inserting retaining plugs one into each end of bore 24. As illustrated in FIGS. 1-3, these end plugs may comprise a pair of composite twopiece plugs 36, 38 and 37, 39. Parts 36 and 37 are cylindrical bodies made of semirigid material such as pyrophyllite, which is a volcanic rock having the property of flowing under high pressure but which upon oozing outside the region of pressure immediately solidifies and prevents any of the charge from escaping. Plugs 36 and 37 are inserted one in each end of bore 24 and pressed against the associated end faces 32 and 34 of charge 26. Next, the other part of the composite end plug, which comprises a disc 38 of rigid metallic material, is inserted endwise one into each end of bore 24 to abut the associated plugs 36 and 37 respectively. Discs 38 and 39 fit closely within bore 24 and are permanently secured to tube 20 as by a peripheral bead of weld 40.

After press 20 is loaded and sealed as described above, it is mechanically engaged at each end by a suitable torque applying device (not shown) such as a wrench mechanism having suitable heads for engaging each of the ends of tube 20 and moment anns for converting stressing forces applied to the free ends of the arms remote from the tube into couples acting coaxially but in opposite directions about the axis 42 of tube 20. To facilitate such interengagement of tube 20 an the torque-applying instrument, the opposite ends of tube 20 in the zones indicated 44 and 46 in FIG. 1 preferably have a noncircular external configuration, such as square, hexagonal or other polygonal shape, or they may be provided with a multiplicity of external teeth or splines adapted to engage complementary internal teeth or splines of the wrench or torque-applying instrument to obtain a positive rather than frictional interengagement. The torque application zones 44 and 46 preferably are at least axially coextensive with end plugs 38 and 39 respectively. Suitable allowance is made for axial shrinkage of tube 20 during torsional stressing thereof as will become evident subsequently herein.

After the torque applying devices are coupled to tube 20, they are actuated to develop oppositely acting couples on the opposite ends of the tube as indicated by arrows 50 and 52 in FIG. 1 so that ends 44 and 46 are twisted in opposite directions. This counterrotational torsional stress causes a deformation of the tube as indicated on an exaggerated scale by the solid line contour of tube 20 shown in FIG. 3 wherein the original unstressed contour of the tube is shown in phantom by dash lines. This deformation can also be seen by comparing the solid line showing of tube 20 in FIG. 1 representing its unstressed condition with dash-dot phantom showing in FIG. 1 illustrating the stress deformed contour of the tube resulting from the torsional stresses diagrammatically represented by dash-dot helical tension stress lines 51. The deformation resulting from this stressing procedure subjects work charge 26 to omnidirectional compressive pressures, i.e., both radial and axial, due to the consequent diametrical reduction of bore 24 and the axially inward movement of end faces 32 and 34 as the end plugs are drawn and squeezed toward one another due to the cumulative effect of axial contraction of tube 20 and the extrusion of the semirigid nose pieces 36 and 37 of the composite end plugs (e.g. FIGS. 2 and 3).

The counterrotational torsional stress is normally applied in a steadily increasing manner until the desired peak stress is achieved. However, the torsional force couples may be applied in any desired predetermined manner, such as in stages with different rates of change in each stage, with or without steady state periods between stages, or at the end of the cycle and/or with force reversals at certain stages of the cycle followed by reapplication of the forces. The torsional force couples may be applied mechanically as described above or through suitable electrically or hydraulically actuated devices as will be well understood by those skilled in high-pressure technology. The rate of application of torsional-stressing forces may be also programmed in terms of the rate of change the temperature of the work charge 26 as it is heated as described hereinafter in a manner best suited to the characteristics of the charge material.

Depending upon the nature of the charge being processed in the torsion press of the invention, as well as the particular method in which the apparatus is employed, removal of the processed charge 26 may be effected by first releasing the stresses for tube 20 and then opening the ends of bore 24 for access to the charge. In most processes of my invention carried out at relatively low temperatures. e.g., at temperatures below those which cause a permanent transformation of the material of tube 20, and wherein nondestructive stresses are employed, such access may be obtained by removing the end plugs and ejecting the compressed and compacted charge from bore 24 with a suitable ejection ram. In high-temperature and/or destructive usages of my apparatus such as those described hereinafter, removal of the processed charge is obtained by cutting through tube 20 slush with the inner ends of the end plugs, or automatically by destruction of tube 20 in the process.

FIGS. 4, and 5 and 6 illustrate a second embodiment of a torsion press in accordance with my invention which comprises a tubular member 100 similar in construction to torsion press 20 except for its external configuration. Tube 100 has a cylindrical external surface 102 which extends axially for the greater part of the overall length of the tube and which terminates by flaring out into integrally connected cylindrical hubs 104 and 106 oflarger diameter than portion 102. The increased diameter of hubs 104 and 106 serves to concentrate the twisting forces on the deformable plugs 36 and in the reduced diameter portion 102 intermediate the hubs. Hence, as best seen by comparing the unstressed and stressed conditions of tube 100 as illustrated in FIGS. 5 and 6 respectively, the deformation of the enlarged ends 104 and 106 will be less than that of the reduced diameter portions 102 in response to a given counterrotational torsional stress applied to ends 104 and 106. The rigid metallic plug 108 which is secured by peripheral weld 110 to hub 104 is generally axially coextensive with the associated hub and tends to support the same against deformation.

FIGS. 7 and 8 illustrates respectively the unstressed and stressed conditions of a torsion press employing tube 100 and deformable inner plug 36 of the second embodiment of FIGS. 46, but the metallic rigid outer part of the composite end plug differs in that it is made in the form of a stul 112 having a hex head 113 disposed externally of hub 104 outwardly of the end face 114 thereof, an externally threaded portion 116 adapted to threadably engage internal threads 118 provided in the end of bore 24, and a smooth cylindrical nose portion 120 adapted to fit closely within the unthreaded portion of bore 24. Plug 112 is thus readily removable from tube 100 and is preferred in those applications in which the torsion press is reusable through several cycles. Plug 112 is also advantageous in providing a convenient device for applying initial axial compacting pressure on the charge 26 prior to torsionally stressing tube 100. An identical plug 112 may be used at the opposite end of tube 100 (not shown) or one of the previously of sub sequently described end plugs may be used at the other end in conjunction with plug 112.

FIGS. 9 and 10 illustrate the unstressed and stressed conditions respectively of a further modification wherein a deformable plug 36 is not used in tube 100. In this instance a removable screw-threaded plug 120 is provided, similar to plug 112, but having a somewhat longer cylindrical nose portion 122, preferably of malleable material or configuration, which fits closely in bore 24 and projects inwardly beyond the inner end of hub 104 so as to axially overlap portion 102, Le, its end face 123 is disposed slightly inwardly of the adjacent end of portion 102 of the tube. With this arrangement of application of counterrotational torsional stress to tube 100 will deform the nose portion 122 of plug 120 to the configuration indicated in FIG. 10 to thereby develop axial pressure on work charge 26 supplemental to the axial compression forces developed through axial contraction of tube 100 in response to twisting thereof.

FIGS. 11 and 12 illustrate the unstressed and stressed conditions respectively of a fifth embodiment wherein a one-piece deformable end plug 130 is secured in the end of bore 24 by a weld 132 similar to plugs 38 and 108. Plug 130 extends inwardly ofend 104 to axially overlap reduced diameter portion 102 so that, upon application of torsional stress to tube 100, the greater concentration of stress in portion 102 will pinch the inner end of plug 132 to thereby deform the nose 134 thereof to the shape shown on an exaggerated scale in FIG. 12.

FIGS. 13 and 14 likewise respectively illustrate tube in its unstressed and stressed conditions with corresponding showings of a hollow, cuplike end plug which is substituted for plug 130. Plug 140 is disposed with its open end flush with end face 114 and with its crowned end wall 142 abutting one end of charge 26. The hollow configuration of plug 140 provides a more readily deformable nose portion 144.

In accordance with one embodiment of the method of my invention, a sintered powder metal stick or rod is formed by using the torsion press of my invention, preferably that described in conjunction with FIGS. 7 and 8 or 9 and 10 in the following manner. The unstressed tube 100 is loaded through its open ends with a charge of powder metal material, such as iron powder or iron oxide powder (Fe o commonly employed in powder metallurgy processes, and the loose powder is rammed with rams inserted into the open ends of bore 24 to initially compact the charge sufficiently to retain it in place in bore 24, Le, at rather low compacting pressures on the order of I00 p.s.i. Next the ends of the bore are plugged by using either the composite removable plug 112-36 or the unitary removable plug 120, these plugs being screwed into the opposite ends of the bore and torqued down sufficiently develop an initial compaction force on the order of 1,000 p.s.i. Then the loaded and sealed tube 100 is subjected to counterrotational torsional stresses as described above so as to twist the ends of the tube in opposite directions, thereby developing omnidirectional compression forces on the iron powder in bore 24 which compact the charge both radially and axially under pressures which may range from about 10,000 p.s.i. to about 100,000 p.s.i. or higher.

The torsion press may be at room temperature or heat may be applied to the press to moderately elevate the temperature thereof, depending on the nature of the material. Altematively, a modified end plug similar to plug 112 may be employed having a screened axial vent hole so that prior to the stressing step the powder charge may be placed under a vacuum by connecting the vent hole in the end plug to a source of subatmospheric pressure to evacuate air from the charge. Preferably the end plug is screwed in gradually during the evacuation step to precompress the charge. The vent hole is then plugged by inserting a rod into the vent hole and welding it to the end face of the plug. The stressing step can also be carried out at reduced temperatures as well as under a vacuum, as in a refrigeration environment, to abstract heat from tube 100 as it is torsionally stressed to compact the charge. The vacuum and reduced temperature environment tend to increase the ultimate density achieved in the compact in the stressing step.

After the stressing step is completed, the stresses are removed, allowing tube 100 to relax. When the tube is made of material such as high-strength steel the gradual release of the torsional stresses will allow the tube to return at least partially to its initial unstressed shape, thereby expanding bore 24 radially and thus facilitating unscrewing of the end plugs as well as axial ejection of the compacted rod formed therein. The powder density of the highly compacted rod, due to the extremely high omnidirectional pressures to which it is subjected, may approach the theoretical density of the material. Due to the radial pressures exerted along the length of the cylindrical surface of the compact during the stressing step, a very desirably improvement in the radially density gradient and axial density gradient is achieved in the rod compact.

The next step is to sinter the compact at the usual sintering temperature for the particular material employed, such as 2,050 F. in case of iron powders, in a reducing atmosphere such as dissociated ammonia for a suitable period of time such as l hour to thereby form a high-strength, smoothly finished rod closely approaching steel in its characteristics. In addition. the finished rod uniformly throughout its length has a higher density adjacent its circumference than at its center due to the radial application of compacting force thereto which in turn makes the rod well suited for transmitting torsional forces in such applications as torsion bar springs and drive shafting.

in another embodiment of the method of my invention extremely high temperatures and pressures are employed to convert a charge of raw material to its crystalline form as for example the conversion of carbon from graphite to diamonds. In this method the graphite raw material in its ordinary powder form is loaded in the torsion press of the invention as described previously, preferably using tube 100 as shown in H08. 4, and 6 and the composite deformable plug 108-36. The loaded and sealed tube 100 is then placed in a heating chamber such as that defined by the space between a pair of refractory walls 150 and 152 illustrated schematically in FIG. 3. The ends of tube 100 project beyond the exterior of the chamber through suitable wall apertures 154 and 156 adapted to closely receive the unstressed tube or 100 coaxially therethrough. Suitable refractory gasketing iris mechanism may be provided at the joint around opening 156 to accommodate, during the subsequent stressing step, radial contraction of the tube which also occurs although to a reduced extent, adjacent the hub ends ofthe tube.

The counterrotational torsional stresses are then applied to the opposite projecting ends of the tube, and simultaneously the work charge 26 of graphite in the tube is heated. The torsional stress is increased generally in step with the increase in temperature until pressures on the order of one million p.s.i. and temperatures above 2,000 P. are obtained in charge 26. Preferably the known catalyst employed in manufacture of industrial diamonds is intermixed with the graphic charge to reduce the ultimate temperature and pressure required to convert the graphite to diamond. impurities may be added, such as boron, beryllium or aluminum, to the starting mixture of the graphite and catalyst if other diamond-type end products are desired such as temperature-sensing diamonds having thermistor characteristics, or other charge mixtures may be used to produce diamonds of gem quality.

The method of heating the compressed graphite charge can be effected in various ways as by an open flame fed by gas, oil or more exotic fuels, or it may be heated by electrical induction equipment. Electrical resistance heating may also be used by passing electrical current axially through bar 20 or 100, suitable electrodes being attached to the ends of the bar. In dealing with the manufacture of exotic materials such as diamonds or other crystalline materials requiring tremendous input of energy to effect the conversion, it is economically feasible to destructively use the torsion press of the invention to obtain an explosive-type application of energy. Preferably the torsional stress is first applied to tube 20 or 100 up to a value below the yield point of the tube material and a relatively low temperature. Then heat is applied to tube 100 or generated therein in a very sudden manner to heat the charge. Preferably this is accomplished by the aforementioned electrical resistance method of heating tube 20 with a vary sudden application of heavy current from a power source such as a bank of storage capacitors adapted to provide a very rapid discharge of current axially through the tube. Suitable protective conditions and equipment are employed in carrying out this explosive-type process inasmuch as under the above conditions tube 20 will shatter with an explosive force, but not before instantaneously applying very high pressures and temperatures to the charge. The disintegration of the torsion press automatically spills its contents within the oven and/or explosion chamber, and after the same has been cooled the debris is sifted to recover the diamond crystals from the scrap material remaining.

The material used for torsional bodies 20 or 100 in the above method is preferably a high-strength refractory metal, i.e.. a metal with a melting point above approximately l,900 C., such as Tungsten, Rhenium, Tantalum, Molybdenum, etc. One satisfactory commercially available material is that known commercially as Climelt TZM, a Molybdenum alloy containing 0.5 percent titanium and 0.8 percent zirconium.

The simple annular cylindrical configuration of the torsional press of the invention leads itself to fabrication from this material by the well-known arc-cast process developed by Climax Molybdenum Company of Michigan, Inc. since it is relatively easy to vacuum arc-cast a heavy wall tube directly to the shape and size required for use in the torsion press of the invention. Hence it is economically feasible to use this relatively expensive material in the expendable torsion press in the crystal-forming process described above.

The simple cylindrical configuration of the torsion press of the invention, and the manner of generating internal pressure therein by applying opposing couples to the ends of the cylinder, provides many other advantages. In those processes employing induction heating, tube 20 or can form the magnetic core of the induction coil which is wrapped helically along the cylindrical surface 22 of the tube and between heat shields and 152 to provide efficient application of the electrical heating field to work charge 26. This mode of heating is advantageous in that, by suitable correlation of the frequency and timing with the material of the charge, the charge can be heated to an elevated temperature before the material of the tube is heated to such temperature. Hence even when running the process to destruction, due to the lag of the tube temperature relative to the charge temperature, the tube will retain adequate strength to exert the extremely high omnidirectional pressures on the charge at a very high charge temperature. From a mechanical and structural standpoint, the simple cylindrical configuration of the torsion press of the invention, and the fact that the torsion-generating devices may be arranged in planes at right angles to the axis of the tube, provides a marked space saving over conventional ram-type presses which require extremely long opposed rams and cylinders and extremely heavy supporting structures. In addition, the torsion press of the invention is capable of applying very high pressures on material in a closed cavity with no relatively moving sliding parts in the press chamber itself, thereby greatly simplifying high-pressure sealing problems.

What is claimed is:

l. A method of subjecting a charge of solid particulate material to high pressure comprising the steps of providing a tubular member having a cavity therein extending in the direction of the axis of the member with an opening connecting the cavity to the exterior of the member, filling the cavity with a charge of the material until the cavity is completely filled with said material, sealing the opening to the cavity, twisting said member by applying counterrotational twisting stresses in planes at right angles to the axis of the member and at spaced points disposed beyond the opposite ends of the charge in said cavity of the member to thereby cause the cavity to contract and transmit the twisting stress to said material in the cavity as a compression force thereon, thereafter at least partially reducing said counterrotational twisting stresses and then while said stresses are thus reduced thereafter removing the compressed material from the cavity as a coherent compacted member.

2. The method as set forth in claim 11 including the further step of heating the charge in the cavity while said member is being stressed.

3. The method as set forth in claim 11 wherein said solid particulate material is a sinterable material and wherein said compacted member after removal from the cavity is maintained at a proper temperature in a proper atmosphere for a sufficient time to sinter the material of the compacted member.

4. A method of subjecting a charge of solid particulate material to high pressure comprising the steps of providing a tubular member having a cavity therein extending in the direction of the axis of the member with an opening connecting the cavity to the exterior of the member, filling the cavity with a charge of the material until the cavity is completely filled with said material, sealing the opening to the cavity, twisting said member by applying counterrotational twisting stresses in planes at right angles to the axis of the member and at spaced points disposed beyond the opposite ends of the charge in said cavity of the member to thereby cause the cavi' ty to contract and transmit the twisting stress to said material in the cavity as a compression force thereon, heating the charge in the cavity while said member is being stressed by passing an electrical current through said charge in the cavity and thereafter removing the compressed material from the cavity.

5. A method of subjecting a charge of solid particulate material to high pressure comprising the steps of providing a tubular member having a cavity therein extending in the direction of the axis of the member with an opening connecting the cavity to the exterior of the member. filling the cavity with a charge of the material until the cavity is completely filled with said material, sealing the opening to the cavity, twisting said member by applying counterrotational twisting stresses in planes at right angles to the axis of the member and at spaced points disposed beyond the opposite ends of the charge in said cavity of the member to thereby cause the cavity to contract and transmit the twisting stress to said material in the cavity as a compression force thereon, heating the charge in the cavity while said member is being stressed by passing an electrical current axially through said member to cause resistance heating of the charge in said cavity and thereafter removing the compressed material from the cavity.

6. The method set forth in claim wherein said resistance heating is accomplished by rapidly discharging a capacitive power source through said member.

7. The method set forth in claim 5 wherein said twisting step is performed by gradually increasing the torsional stress applied in opposite directions to said member while heating said charge in the cavity of said member for a predetermined period of time, and wherein said resistance heating step includes applying electrical heating current to said member sufficient to disintegrate said member subsequent to said period of time.

8. A method of subjecting a charge of solid particulate material to high pressure comprising the steps of providing a tubular member having a cavity therein extending in the direction of the axis of the member with an opening connecting the cavity to the exterior of the member, filling the cavity with a charge of the material until the cavity is completely filled with said material, sealing the opening to the cavity, twisting said member by applying counterrotational twisting stresses in planes at right angles to the axis of the member and at spaced points disposed beyond the opposite ends of the charge in said cavity of the member to thereby cause the cavity to contract and transmit the twisting stress to said material in the cavity as a compression force thereon, said twisting forces being applied to said member at an increasing rate until destructive stresses are reached and said member is ruptured, and thereafter removing the compressed material from the cavity.

.WWW I vvUML'UA) b'l'A-l'bb mum urr un CERTIFICATE 0 CORRECTION Patent No; 3, 0, 7 a December 28, 1971 Peter F. Rossmann It is certified that error appears in the above-identified patent and that said Letters Patent are he'rebycorrected as shown below:

a" y A *1 In the title, cancel "APPARATUS AND" In the Abstract, lines'l and 2, cancel "and apparatus for use in the method,"

Column 1 line ll, after "destruction" insert -in--; line 56, cancel "change" and insert charge-.

Column 2 line 16, cancel "an" and insert -and--; line 18, cancel "instrument" and insert -in'strument-s-; line 74, cancel "for" (first occurrence) and insert -from.

Column 3 line 10, cancel "slush" and insert flush-; line 12, cancel "and" (first occurrence) 5 line 27, cancel "portions" and insert --port'ion; line 33, cancel "illustrates" and insert -illust-rate-- line 55, after "screwthreaded" insert -end; line 62, cancel "of (third occurrence) and insert -the-.

Column 4 line 66, cancel "radially" and insert radial.

Column 5 line 31', cancel "graphic" and insert graphite.

Column 6 line 2, cancel "leads" and insert -'-lends-;

line 7, cancel "relatively" and insert --relative-; line 58, cancel "ll" and insert --l-7 line 61, cancel "11" and insert Signed and sealed this 6th day of June 1972.

(SEAL) Attest:

EDWARD NLPLETCHERJR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents Patent: No.

5 UNlTED STATES PATENT OFFICE I @ERTIFICATE OF CORRECTION 3,639, 727 Dated, December 28, 1971 Inventor-(s) eter F. Rossmann It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the title, cancel "APPARATUS AND" In the Abstract, lines'l and 2, cancel "and apparatus for use in the method, I

line ll, after "destruction" insert -in--; "change" and insert -charge-.

Column 1 line 56, cancel line 16, cancel "an" and insert -and--;

Column 2 line 18, cancel "instrument" and insert -instruments-; line 74, cancel "for" (first occurrence) and insert --from-.

Column 3 e line 10, cancel "slush" and insert flush; line 12, cancel "and" (first occurrence) 5 line 27, cancel "portions and insert --port ion-; line 33, cancel "illustrates" and insert --illustrate-- line 55, after "screwthreaded" insert -end--; line 62, cancel "of" (third occurrence) and insert -the--.

Column 4 line 66, cancel "radially" and insert radial.

Column 5 line 31', cancel "graphic" and insert -graphite.

Column 6 line 2, cancel "leads" and insert lends--; line 7 cancel "relatively" and insert -'re lative; line 58,

cancel "ll" and insert -l--; line 61, cancel "11" and insert Signed and sealed this 6th day of June 1972.

(SEAL) Attest:

ROBERT GOTTSCHALK Commissioner of Patents EDWARD TI.PLETCHER,JR. Attesting Officer 

2. The method as set forth in claim 11 including the further step of heating the charge in the cavity while said member is being stressed.
 3. The method as set forth in claim 11 wherein said solid particulate material is a sinterable material and wherein said compacted member after removal from the cavity is maintained at a proper temperature in a proper atmosphere for a sufficient time to sinter the material of the compacted member.
 4. A method of subjecting a charge of solid particulate material to high pressure comprising the steps of providing a tubular member having a cavity therein extending in the direction of the axis of the member with an opening connecting the cavity to the exterior of the member, filling the cavity with a charge of the material until the cavity is completely filled with said material, sealing the opening to the cavity, twisting said member by applying counterrotational twisting stresses in planes at right angles to the axis of the member and at spaced points disposed beyond the opposite ends of the charge in said cavity of the member to thereby cause the cavity to contract and transmit the twisting stress to said material in the cavity as a compression force thereon, heating the charge in the cavity while said member is being stressed by passing an electrical current through said charge in the cavity and thereafter removing the compressed material from the cavity.
 5. A method of subjecting a charge of solid particulate material to high pressure comprising the steps of providing a tubular member having a cavity therein extending in the direction of the axis of the member with an opening connecting the cavity to the exterior of the member, filling the cavity with a charge of the material until the cavity is completely filled with said material, sealing the opening to the cavity, twisting said member by applying counterroTational twisting stresses in planes at right angles to the axis of the member and at spaced points disposed beyond the opposite ends of the charge in said cavity of the member to thereby cause the cavity to contract and transmit the twisting stress to said material in the cavity as a compression force thereon, heating the charge in the cavity while said member is being stressed by passing an electrical current axially through said member to cause resistance heating of the charge in said cavity and thereafter removing the compressed material from the cavity.
 6. The method set forth in claim 5 wherein said resistance heating is accomplished by rapidly discharging a capacitive power source through said member.
 7. The method set forth in claim 5 wherein said twisting step is performed by gradually increasing the torsional stress applied in opposite directions to said member while heating said charge in the cavity of said member for a predetermined period of time, and wherein said resistance heating step includes applying electrical heating current to said member sufficient to disintegrate said member subsequent to said period of time.
 8. A method of subjecting a charge of solid particulate material to high pressure comprising the steps of providing a tubular member having a cavity therein extending in the direction of the axis of the member with an opening connecting the cavity to the exterior of the member, filling the cavity with a charge of the material until the cavity is completely filled with said material, sealing the opening to the cavity, twisting said member by applying counterrotational twisting stresses in planes at right angles to the axis of the member and at spaced points disposed beyond the opposite ends of the charge in said cavity of the member to thereby cause the cavity to contract and transmit the twisting stress to said material in the cavity as a compression force thereon, said twisting forces being applied to said member at an increasing rate until destructive stresses are reached and said member is ruptured, and thereafter removing the compressed material from the cavity. 